Total synthesis of (-)-ent-pachastrissamine (ent-Jaspine B)

Article abstract of DOI:10.1016/j.tetasy.2011.07.010

The total synthesis of the enantiomer of the tetrahydrofuran containing natural product Jaspine B is reported. The key reactions in the synthesis include formation of the tetrahydrofuran unit by an acid mediated Williamson etherification and a subsequent

Full text of DOI:10.1016/j.tetasy.2011.07.010

Tetrahedron: Asymmetry 22 (2011) 1400–1403
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Total synthesis of (À)-ent-pachastrissamine (ent-Jaspine B)
⇑
Kavirayani R. Prasad , Kamala Penchalaiah
Department of Organic Chemistry, Indian Institute of Science, Bangalore 560 012, India
a r t i c l e i n f o
a b s t r a c t
Article history:
The total synthesis of the enantiomer of the tetrahydrofuran containing natural product Jaspine B is
reported. The key reactions in the synthesis include formation of the tetrahydrofuran unit by an acid
mediated Williamson etherification and a subsequent elaboration with an olefin cross metathesis
reaction.
Received 15 June 2011
Accepted 12 July 2011
Available online 14 September 2011
Ó 2011 Elsevier Ltd. All rights reserved.
1. Introduction
masked tetrol 6, while installation of the amine is anticipated by
displacement of the secondary tosylate in 5 with benzylamine.
Pachastrissamine (Jaspine B) 1 is a tetrahydrofuran containing
natural product with three contiguous stereogenic centers isolated
from the Okinawan marine sponge and also from the marine
sponge Jaspis sp. (hence the name Jaspine B).1,2 Pachastrissamine
Elaboration of the olefin in 4 by cross metathesis with 1-tridecene
was envisaged for the installation of the C14 side-chain.
The synthetic sequence commenced with the conversion of the
known homoallylic alcohol 88 to the MOM ether 6, which upon
deprotection of the acetonide afforded diol 9 in excellent yield.
The reaction of diol 9 with p-toluenesulfonyl chloride in the pres-
ence of DMAP afforded the di-tosylate 10 in 95% yield. We in-
1 is structurally similar to the open chain sphingolipid D-ribo-phy-
tosphingosine 2 and was found to be marginally active against the
A549 human lung carcinoma cell line, and at a submicromolar level
against HT29, MEL28 and P388 cancer cell lines.3
tended to synthesize tetrahydrofuran
5 by intramolecular
Williamson etherification of the hydroxy tosylate 10a. However,
the attempted deprotection of MOM ether in 10 with PPTS fur-
nished the tetrahydrofuran 5 directly in 94% yield. Stereospecific
SN2 displacement of the tosylate 5 with benzylamine afforded 4
in 86% yield as a single diastereoisomer.9 Cross metathesis of 4
with 1-tridecene using Grubbs’ first generation catalyst produced
3 in 78% yield. Debenzylation of the amine and alcohol in 3 with
Pd(OH)2 under hydrogenation conditions proved to be inefficient
and no product could be isolated. However, hydrogenation of 3
in the presence of trifluoroacetic acid cleanly produced the TFA salt
of ent-Jaspine B 11 in 93% yield, which upon treatment with meth-
anolic NaOH furnished ent-Jaspine B ent-1 in 95% yield (Scheme 2).
The spectroscopic data of ent-Jaspine B ent-1 were in complete
agreement with the data reported for the natural product by Kur-
oda et al.
NH2 OH
H2N
OH
HO
C14H29
C14H29
O
OH
pachastrissamine
D-ribo-phytosphingosine 2
(Jaspine B) 1
There have been many publications on the synthesis of 1 and its
analogues in recent years.4 Most of the syntheses originate from
chiral pool precursors, such as carbohydrates, the aminoacid serine
and from tartaric acid; syntheses involving asymmetric transfor-
mations have also been reported.5 We have reported an efficient
synthesis of 1 from tartaric acid involving the use of a c-hydroxy
amide derived from tartaric acid as the key building block.6 Re-
cently, we used the masked tetrol 6 derived from the erythritol 7
in our synthesis of the bio-active lactone synargentolide A.7 In con-
tinuation of the application of the masked tetrol 6, we herein re-
port the synthesis of ent-Jaspine B.
3. Conclusion
2. Results and discussion
In conclusion, a short synthetic sequence for (À)-ent-Jaspine B
has been reported starting from an erythritol derived from tartaric
acid. The key reactions in the synthesis include the formation of
the tetrahydrofuran unit by an acid mediated Williamson etherifi-
cation and a subsequent elaboration with an olefin cross metathe-
sis reaction.
The present approach for ent-Jaspine B is outlined in Scheme 1.
We decided to construct the THF unit 5 by elaboration of the
⇑
Corresponding author. Fax: +91 80 23600529.
E-mail address: prasad@orgchem.iisc.ernet.in (K.R. Prasad).
0957-4166/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetasy.2011.07.010

K. R. Prasad, K. Penchalaiah / Tetrahedron: Asymmetry 22 (2011) 1400–1403
1401
BnHN
OBn
BnHN
OBn
H2N
OH
C14H29
O
O
O
9
4
1
ent-
3
OBn
OBn
TsO
OBn
OH
O
O
O
OMOM
O
O
7
6
5
Scheme 1. Retrosynthesis for (À)-ent-Jaspine B 1.
i) MOMCl, iPr2NEt, DCM
OBn
OBn
OBn
OH
ref. 8
0°C to rt, 3h, 77%
ii) PPTS, MeOH, rt, 12h
81%;
HO
O
O
O
OH
O
OH OMOM
7
9
8
OBn
TsO
OBn
BnNH2, 150 °C
12 h, 86%
PPTS, MeOH
reflux, 1 h, 94%
TsCl, DMAP, CH2Cl2
TsO
0 °C to rt, 12 h, 95%
OTs OR
O
R = MOM 10
5
R = H 10a
BnHN
OBn
BnHN
OBn
Grubbs' 1st gen. catalyst
1-trideccene, CH2Cl2
reflux, 12 h, 78%
Pd(OH)2/H2, TFA
MeOH, 12 h, 93%
Me
9
O
O
4
3
H2N
OH
H3N
OH
2.5 M methanolic NaOH
CH2Cl2, rt, 15min, 95%
TFA
C14H29
O
C14H29
O
11
ent-1
Scheme 2. Total synthesis of (À)-ent-Jaspine B.
for 3 h and after completion of the reaction (TLC), it was poured
into cold water (15 mL) and extracted with EtOAc (3 Â 10 mL).
The organic layer was washed with brine (5 mL) and dried over
Na2SO4. The residue obtained after concentration was purified by
column chromatography using petroleum ether/ethyl acetate
(4:1) as eluent to yield the corresponding MOM ether (0.18 g) in
4. Experimental
4.1. General
Column chromatography was performed on silica gel, Acme
grade 100–200 mesh. TLC plates were visualized either with UV,
in an iodine chamber, or with phosphomolybdic acid spray, unless
noted otherwise. Unless stated otherwise, all reagents were pur-
chased from commercial sources and used without additional puri-
fication. THF was freshly distilled over Na-benzophenone ketyl.
Melting points are uncorrected. Unless stated otherwise, 1H NMR
and 13C NMR spectra were recorded either on a Bruker AC400 or
on a JEOL300 machine in CDCl3 as solvent with TMS as reference
unless otherwise indicated. Unless stated otherwise, all the reac-
tions were performed under an inert atmosphere.
77% yield as a colorless oil. [
a
]
D = À46.2 (c 0.8, CHCl3); IR (neat)
2986, 2888, 1370, 1156, 1036 cmÀ1
;
1H NMR (400 MHz, CDCl3) d
7.38–7.16 (m, 5H), 5.62 (ddt, J = 16.8, 9.4, 7.0 Hz, 1H), 5.02–4.89
(m, 2H), 4.77, 4.65 (ABq, J = 11.8 Hz, 2H), 4.57, 4.53 (ABq,
J = 6.9 Hz, 2H), 4.31 (dd, J = 14.0, 7.3 Hz, 1H), 3.97 (dd, J = 8.2,
6.2 Hz, 1H), 3.63 (t, J = 8 Hz, 1H), 3.55 (ddd, J = 10.0, 6.5, 3.6 Hz,
1H), 3.37 (dd, J = 7.0, 3.4 Hz, 1H), 3.28 (s, 3H), 2.52–2.35 (m, 1H),
2.30–2.13 (m, 1H), 1.37 (s, 3H), 1.32 (s, 3H); 13C NMR (100 MHz,
CDCl3) 138.4 (Cq), 134.7 (CH), 128.23 (CH), 128.21 (CH), 127.5
(CH), 117.5 (CH2), 108.9 (Cq), 96.2 (CH2), 79.6 (CH), 77.3 (CH),
77.03 (CH), 73.7 (CH2), 66.0 (CH2), 55.9 (CH3), 35.2 (CH2), 26.6
(CH3), 25.7 (CH3); HRMS for C19H28O5 + Na calcd 359.1834; found
359.1830.
4.1.1. (2S,3R,4R)-3-(Benzyloxy)-4-(methoxymethoxy)hept-6-
ene-1,2-diol 9
To a pre-cooled (0 °C) solution of 8 (0.20 g, 0.68 mmol), in
CH2Cl2 (3 mL) was added diisopropylethylamine (0.59 mL,
3.42 mmol), followed by MOMCl (0.2 mL, 2.73 mmol) under argon
atmosphere. The reaction mixture was stirred at room temperature
To a stirred solution of the MOM ether prepared above (0.052 g,
0.15 mmol), in MeOH (1 mL), was added PPTS (8 mg, 0.03 mmol).
The reaction mixture was stirred at room temperature for 12 h,

1402
K. R. Prasad, K. Penchalaiah / Tetrahedron: Asymmetry 22 (2011) 1400–1403
after which NaHCO3 (0.015 g) was added and stirred for 10 min.
The reaction mixture was filtered through a short pad of Celite
and the Celite pad was washed with EtOAc (10 mL). The residue
obtained after evaporation of the solvent was purified by column
chromatography using petroleum ether/EtOAc (2:3) as eluent to
(CH), 71.9 (CH2), 70.7 (CH2), 32.8 (CH2), 21.7 (CH3); HRMS for
21H24O5S + Na calcd 411.1242; found 411.1246.
C
4.1.4. (3R,4R,5R)-5-Allyl-N-benzyl-4-(benzyloxy)tetrahydro-
furan-3-amine 4
obtain the diol
D = +3.7 (c 4.0, CHCl3); IR (neat) 3430, 2932, 2891, 1101,
1036 cmÀ1 1H NMR (400 MHz, CDCl3) d 7.42–7.20 (m, 5H), 5.83
9
(0.037 g) in 81% yield as
a
colorless oil.
Benzylamine (1 mL) was added to tosylate 5 (0.125 g,
[a
]
0.32 mmol) and heated to 150 °C for 12 h. After completion of
the reaction (TLC), it was purified by column chromatography
without work-up using petroleum ether/EtOAc (3:2) as eluent to
;
(ddt, J = 17.1, 10.2, 7.0 Hz, 1H), 5.12 (dd, J = 16.4, 1.2 Hz, 1H),
4.77, 4.59 (ABq, J = 11.3 Hz, 2H), 4.69, 4.67 (ABq, J = 6.8 Hz, 2H),
3.92–3.80 (m, 2H), 3.63 (d, J = 5.2 Hz, 2H), 3.54 (t, J = 4.7 Hz, 1H),
3.37 (s, 3H), 2.59 (br s, 1H), 2.56–2.45 (m, 1H), 2.44–2.30 (m,
1H), 2.28 (br s, 1H); 13C NMR (100 MHz, CDCl3) 137.6 (Cq), 134.6
(CH), 128.4 (CH), 128.07 (CH), 128.0 (CH), 117.4 (CH2), 96.6
(CH2), 79.6 (CH), 77.1 (CH), 74.1 (CH2), 70.8 (CH), 64.0 (CH2), 55.7
(CH3), 35.2 (CH2); HRMS for C16H24O5 + Na calcd 319.1521; found
319.1519.
obtain 4 (0.089 g) in 86% yield as a yellow oil. [
a]
D = +51.0 (c 1.9,
CHCl3); IR (neat) 3334, 2924, 2864, 1640, 1065 cmÀ1
;
1H NMR
(400 MHz, CDCl3) d 7.42–7.20 (m, 10H), 5.87 (ddt, J = 17.0, 10.3,
6.8 Hz, 1H), 5.15 (d, J = 17.2 Hz, 1H), 5.09 (d, J = 10.2 Hz, 1H),
4.74, 4.59 (ABq, J = 11.4 Hz, 2H), 4.05–3.88 (m, 3H), 3.72, 3.68
(ABq, J = 13.6 Hz, 2H), 3.60 (t, J = 8.7 Hz, 1H), 3.45 (td, J = 8.4,
4.5 Hz, 1H), 2.63–2.39 (m, 2H), 1.87 (br s, 1H); 13C NMR
(100 MHz, CDCl3) 140.2 (Cq), 138.1 (Cq), 135.1 (CH), 128.5 (CH),
128.4 (CH), 128.0 (CH), 127.9 (CH), 127.8 (CH), 127.0 (CH), 116.8
(CH2), 81.6 (CH), 78.3 (CH), 74.4 (CH2), 70.6 (CH2), 61.1 (CH), 52.2
(CH2), 34.6 (CH2); HRMS for C21H25NO2 + Na calcd 346.1783; found
346.1784.
4.1.2. (2S,3S,4R)-3-(Benzyloxy)-4-(methoxymethoxy)hept-6-
ene-1,2-diyl methylbenzenesulfonate 10
To a stirred solution of diol 9 (0.105 g, 0.35 mmol) in CH2Cl2
(2 mL) was added DMAP (0.216 g, 1.77 mmol), followed by p-TsCl
(0.269 g, 1.41 mmol) at 0 °C under an argon atmosphere. The reac-
tion mixture was stirred for 12 h at room temperature. After com-
pletion of the reaction (TLC), it was poured into water (5 mL) and
extracted with diethyl ether (2 Â 5 mL). The combined organic ex-
tracts were washed with brine (5 mL) and dried over Na2SO4. Evap-
oration of the solvent followed by column chromatography of the
resulting residue using petroleum ether/EtOAc (7:3) as eluent
4.1.5. (3R,4R,5R)-N-Benzyl-4-(benzyloxy)-5-((E)-tetradec-2-en-
1-yl)tetrahydrofuran-3-amine 3
To a stirred solution of 4 (0.052 g, 0.16 mmol) and 1-tridecene
(0.146 g, 0.8 mmol) in CH2Cl2 (0.5 mL) was added Grubbs’ first gen-
eration catalyst (0.040 g, 0.048 mmol) and refluxed for 12 h. After
completion of the reaction (TLC), it was filtered through a short
pad of silica gel and the silica gel pad was washed with diethyl
ether (20 mL). Evaporation of the solvent and purification of the
resulting residue by column chromatography using petroleum
ether/EtOAc (7:3) as eluent furnished 3 (0.060 g) in 78% yield as
yielded 10 (0.201 g) in 95% yield as a colorless oil. [
a]
D = À15.2 (c
3.8, CHCl3); IR (neat) 2922, 1367, 1177, 1033, 916 cmÀ1
;
1H NMR
(400 MHz, CDCl3) d 7.70 (d, J = 8.1 Hz, 2H), 7.66 (d, J = 8.1 Hz, 2H),
7.36–7.17 (m, 9H), 5.60 (ddt, J = 17.2, 10.0, 7.1 Hz, 1H), 5.03 (d,
J = 11.5 Hz, 1H), 5.0 (d, J = 18.4 Hz, 1H), 4.82 (td, J = 5.8, 2.6 Hz,
1H), 4.58, 4.54 (ABq, J = 7.0 Hz, 2H), 4.52 (s, 2H), 4.32 (dd,
J = 11.6, 2.8 Hz, 1H), 4.24 (dd, J = 11.6, 5.2 Hz, 1H), 3.81–3.64 (m,
2H), 3.28 (s, 3H), 2.44 (s, 3H), 2.42 (s, 3H), 2.40–2.18 (m, 2H); 13C
NMR (100 MHz, CDCl3) 145.14 (Cq), 145.08 (Cq), 137.3 (Cq),
133.7 (CH), 133.1 (CH), 132.3 (CH), 129.9 (CH), 129.8 (CH), 128.4
(CH), 128.3 (CH), 128.0 (CH), 118.1 (CH2), 96.2 (CH2), 78.5 (CH),
77.1 (CH), 75.5 (CH), 74.4 (CH2), 68.1 (CH2), 56.2 (CH3), 34.9
(CH2), 21.7 (CH3); HRMS for C30H36O9S2 + Na calcd 627.1698;
found 627.1687.
a brown oil. [
a]
D = +25.6 (c 0.4, CHCl3); IR (neat) 3338, 2923,
2852, 1606, 1457, 1026 cmÀ1
;
1H NMR (400 MHz, CDCl3) d 7.41–
7.20 (m, 10H), 5.63–5.48 (m, 1H), 5.47–5.35 (m, 1H), 4.74, 4.58
(ABq, J = 11.5 Hz, 2H), 3.98 (t, J = 7.9 Hz, 1H), 3.94–3.83 (m, 2H),
3.71, 3.67 (ABq, J = 13.5 Hz, 2H), 3.58 (t, J = 8.3 Hz, 1H), 3.44 (br
d, J = 3.5 Hz, 1H), 2.58–2.37 (m, 2H), 2.0 (td, J = 16.8, 9.4 Hz, 2H),
1.87 (br s, 1H), 1.37–1.21 (m, 18H), 0.89 (t, J = 6.4 Hz, 3H); 13C
NMR (100 MHz, CDCl3) 140.1(Cq), 138.2 (Cq), 133.2 (CH), 128.5
(CH), 128.4 (CH), 128.0 (CH), 127.8 (CH), 127.1 (CH), 126.1 (CH),
82.4 (CH), 78.1 (CH), 74.4 (CH2), 70.5 (CH2), 61.2 (CH), 52.5 (CH2),
33.3 (CH2), 32.7 (CH2), 31.9 (CH2), 29.7 (CH2), 29.56 (CH2), 29.50
(CH2), 29.4 (CH2), 29.3 (CH2), 22.7 (CH2), 14.2 (CH3); HRMS for
4.1.3. (3S,4S,5R)-5-Allyl-4-(benzyloxy)tetrahydrofuran-3-yl 4-
methylbenzenesulfonate 5
C32H47NO2 + Na calcd 478.3685; found 478.3680.
To a stirred solution of the di-tosylate 10 (0.070 g, 0.11 mmol),
in MeOH (1.5 mL), was added PPTS (0.029 g, 0.11 mmol). The reac-
tion mixture was refluxed for 1 h, and after completion of the reac-
tion (TLC), NaHCO3 (0.050 g) was added and stirred for 10 min. The
reaction mixture was filtered through a short pad of Celite and the
Celite pad was washed with EtOAc (15 mL). The residue obtained
after evaporation of the solvent was purified by column chroma-
tography using petroleum ether/EtOAc (4:1) as eluent to obtain 5
4.1.6. Synthesis of 11
To a solution of 3 (0.040 g, 0.083 mmol) in MeOH (1.5 mL), tri-
fluoroacetic acid (0.2 mL, 2.51 mmol) was added and degassed.
Next, Pd(OH)2/C (0.01 g) was added to the reaction mixture and
stirred under hydrogen atmosphere (balloon) for 12 h. After com-
pletion of the reaction (TLC), it was filtered through a short pad
of Celite and the Celite pad was washed with 1:1 MeOH/CHCl3
(20 mL). The residue obtained after concentration of the solvent
was purified by column chromatography using MeOH/CHCl3
(1:4) as eluent to furnish the TFA salt 11 (0.036 g) in 93% yield as
(0.40 g) in 94% yield as a colorless oil. [
a]
D = À44.7 (c 1.1, CHCl3);
IR (neat) 2946, 2876, 1367, 1177, 1096, 962 cmÀ1
;
1H NMR
(400 MHz, CDCl3) d 7.78 (d, J = 8.1 Hz, 2H), 7.35–7.29 (m, 5H),
7.27 (d, J = 6.9 Hz, 2H), 5.75 (ddt, J = 17.2, 10.4, 7.0 Hz, 1H), 5.09
(d, J = 17.2 Hz, 1H), 5.03 (d, J = 10.2 Hz, 1H), 4.95 (br d, J = 4.5 Hz,
1H), 4.58, 4.42 (ABq, J = 11.9 Hz, 2H), 4.13 (dd, J = 10.9, 5.1 Hz,
1H), 4.04–3.90 (m, 2H), 3.69 (d, J = 10.9 Hz, 1H), 2.46 (s, 3H),
2.51–2.30 (m, 2H); 13C NMR (100 MHz, CDCl3) 145.3 (Cq), 137.3
(Cq), 134.3 (CH), 133.4 (Cq), 130.1 (CH), 128.5 (CH), 128.0 (CH),
127.84 (CH), 127.78 (CH), 117.2 (CH2), 82.5 (CH), 82.0 (CH), 80.2
a white solid. mp 106–111 °C; [
a
]
D = À16.4 (c 0.4, EtOH); lit5a
[a]D = +17.1 (c 0.4, EtOH) for the enantiomer; IR (neat) 3446,
2921, 2850, 1670, 1208, 1180, 1147 cmÀ1 1H NMR (400 MHz,
;
CD3OD) d 4.25 (t, J = 4.6 Hz, 1H), 3.99–3.80 (m, 2H), 3.80 (dd,
J = 8.0, 4.7 Hz, 1H), 3.71 (td, J = 6.6, 3.4, Hz, 1H), 1.72–1.58 (m,
2H), 1.41–1.23 (br m, 24H), 0.9 (t, J = 6.3 Hz, 3H); 13C NMR
(100 MHz, CD3OD) 84.4 (CH), 70.9 (CH), 68.9 (CH2), 54.3 (CH),
33.1 (CH2), 30.9 (CH2), 30.8 (CH2), 30.7 (CH2), 30.5 (CH2), 29.7

K. R. Prasad, K. Penchalaiah / Tetrahedron: Asymmetry 22 (2011) 1400–1403
1403
3. (a) Canals, D.; Mormeneo, D.; Fabriàs, G.; Llebaria, A.; Casas, J.; Delgado, A.
Bioorg. Med. Chem. 2009, 17, 235; (b) Liu, J.; Du, Y.; Dong, X.; Meng, S.; Xiao, J.;
Cheng, L. Carbohydr. Res. 2006, 341, 2653.
4. For a review on the synthesis of jaspine B see: Abraham, E.; Davies, S. G.;
Roberts, P. M.; Russell, A. J.; Thomson, J. E. Tetrahedron: Asymmetry 2008, 19,
1027.
(CH2), 27.2 (CH2), 23.7 (CH2), 14.5 (CH3); Anal. Calcd for
20H38F3NO4: C, 58.09; H, 9.26; N, 3.39. Found: C, 57.63; H, 9.05;
N, 3.74.
C
4.1.7. Synthesis of (À)-ent-Jaspine B ent-1
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Chattopadhyay, A. Tetrahedron: Asymmetry 2010, 21, 1983; (x) Llaveria, J.; Diaz,
Y.; Matheu, M. I.; Castillon, S. Eur. J. Org. Chem. 2011, 1514; (y) Passiniemi, M.;
Koskinen, A. M. P. Org. Biomol. Chem. 2011, 1774.
To a stirred solution of 11 (0.025 g, 0.06 mmol) in CH2Cl2 (1 mL)
was added 2.5 M methanolic NaOH (1 mL) solution at room tem-
perature and stirred at room temperature for 15 min. The residue
was purified by column chromatography without any work-up,
using MeOH/CHCl3 (1:4) containing 2% NH4OH solution as eluent
to yield 1 (0.017 g) in 95% yield as a white solid. mp 91–93 °C; lit5i
mp 90–92 °C; [
a]
D = À17.7 (c 0.4, EtOH); lit5i
[
a]
D = +17.5 (c 0.3,
EtOH); IR (neat) 3342, 2921, 2850, 1470, 1035 cmÀ1
;
1H NMR
(400 MHz, CD3OD) d 3.90 (t, J = 7.6 Hz, 1H), 3.86 (t, J = 3.5 Hz,
1H), 3.81 (td, J = 6.9, 2.6 Hz, 1H), 3.51 (td, J = 7.8, 4.3 Hz, 1H), 3.43
(dd, J = 8.7, 7.9 Hz, 1H), 1.72–1.48 (m, 2H), 1.42–1.23 (br m, 24H),
0.9 (t, J = 7.0 Hz, 3H); 13C NMR (100 MHz, CD3OD) 84.3 (CH), 73.2
(CH), 72.0 (CH2), 56.0 (CH), 33.1 (CH2), 30.9 (CH2), 30.8 (CH2),
30.7 (CH2), 30.55 (CH2), 30.49 (CH2), 27.1 (CH2), 23.7 (CH2), 14.5
(CH3); HRMS for C18H37NO2 + H calcd 300.2903; found 300.2901.
Acknowledgments
We thank the Department of Science and Technology (DST),
New Delhi for funding. K.R.P. is a swarnajayanthi fellow of DST,
New Delhi. K.P. thanks Council of Scientific and Industrial Research
(CSIR), New Delhi for a senior research fellowship.
References
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9. It is noteworthy that the reaction of tosylate 5 with sodium azide failed to
produce the corresponding azide.
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